Potassium supplements and potassium-sparing diuretics. A review and guide to appropriate use.

Epidemiological and clinical studies suggest that low dietary potassium intake may have an important role in determining the development of diseases such as hypertension, and perhaps even stomach cancer, and that increased potassium intake may have beneficial effects in several other conditions. Dietary adjustment or active potassium supplementation has been suggested as a natural, less costly and safe method of increasing potassium levels, although active supplementation with tablets or solutions is not recommended in healthy people with normal serum potassium levels. However, increasing dietary potassium intake in the elderly and in patients with renal impairment must be considered with caution. Diuretics have a long established role in the management of hypertension and heart failure. There is no convincing evidence to suggest that the small reduction in plasma potassium levels associated with low dose thiazide and loop diuretic therapy needs to be routinely prevented by the use of potassium-sparing drugs. In non-digitalised patients little association has been found between mild diuretic-induced hypokalaemia and arrhythmias. Thus, the routine prophylactic use of potassium-sparing diuretics in combination with non-potassium-retaining diuretics for the treatment of hypertension and oedematous states is not justified. Based on current evidence, treating all patients whose serum potassium level decreases below 3 mmol/L is recommended, although for certain patients at particular risk of hypokalaemia, levels may need to be maintained above 3.5 mmol/L. In overt hypokalaemia, several therapeutic options are available to the clinician. These include increased consumption of potassium-rich foods, the use of salt substitutes, medicinal potassium supplementation or distal tubular (potassium-sparing) diuretics.